a) Field of the Invention
The present invention relates to a ship, and more particularly to a ship hull which is provided with a main hull and a movable rearbody having an engine and a propeller, with the movable rearbody being pivoted at a stern of the main hull by a hinge coupling device that the rearbody is able to move upward and downward with respect to the main hull.
b) Description of the Prior Art
A ship hull is divided into a fore and aft hull sections, and confronting ends of the fore and aft hull sections are connected as an integral unit by a hinge coupling device to constitute an articulated ship, such as U.S. Pat. Nos. 3,145,681 (issued to ETSUO NAKAGAWA), 3,370,564 (issued to G. ARCHER, et al.), 4,050,395 (issued to ANDERSON) and 6,431,099 (issued to HUANG, the present inventor). All the design objects of these articulated ship structures are to increase a capability of the hulls to overcome hogging and sagging resulted from pitching which occurs when the ships ride on waves during sailing.
U.S. Pat. No. 3,145,681 discloses that a hinge coupling portion of two hull sections is formed by at least one half-cylindrical projection of one hull section, at least one half-cylindrical concave portion of the other hull section to engage with the half-cylindrical projection, and transversal shafts which penetrate center portions of the projections and the concave portions that are engaged, thereby connecting the two hull sections as one integral unit with one hull section being rotatable relative to the other hull section.
U.S. Pat. No. 3,370,564 discloses a structural improvement to the hinge coupling device as described in the aforementioned U.S. Pat. No. 3,145,681 by increasing a radius of the hinge coupling device to give greater bending relationship to the hull sections and to extend an arc below a base line of the ship.
U.S. Pat. No. 4,050,395 discloses a hinge coupling device which is applied to the aforementioned articulated ship. However, this hinge coupling device is different from the aforementioned hinge coupling devices by being provided with a pivot means which interconnects the fore and aft hull sections for relative pivoting, and a connecting means which is away from the pivot means and is used to interconnect the two hull sections to adjustably yieldingly resist a relative angular displacement of the hull sections, with the pivot means including an adjustment means for adjustably vertically shifting one section relative to the other section.
U.S. Pat. No. 6,431,099 issued to the present inventor discloses a hinge coupling device which is applied to the aforementioned articulated ship. The hinge coupling device includes a hinge block which forms part of the ship hull, and an interior of which is provided with a complete hinge assembly. This hinge block is constituted by a hull-type front hinge portion, a hull-type rear hinge portion and the aforementioned hinge assembly which is pivotally provided between the front and rear hinge portions to connect these two hinge portions, wherein one hinge portion is detachably connected to one of the fore and aft hull sections, and the other hinge portion is fixed at the other one of the fore and aft hull sections. By this structure, the fore and aft hull sections which are connected as one integral body can be separated when necessary.
The articulated ship structures disclosed in the aforementioned patents are provided with one common function to reduce a bending moment that acts on the hull from pitching which occurs when the ship rides on waves. In other words, this common function is to increase resistance of the hull to the hogging and sagging resulted from the waves. However, these patents never disclose nor imply that when this kind of articulated ship sets sail or navigates, the rearbody can be lifted up or put down by a hoisting method to adjust a pitching angle with respect to the forebody, thereby adjusting a propeller at a desired waterline height or setting the propeller to sway in the adjusted pitching angle.
Moreover, for the aforementioned conventional articulated ship structure, the hinge coupling device of the fore and aft hull sections is directly exposed outside, which is indecent to be looked at and is dangerous.